1. Field of the Invention
The present invention relates to a gas generator for an air bag for protecting a passenger from an impact.
2. Description of Related Art
A gas generator for an air bag incorporated in an air bag system mounted in an automobile needs to satisfy various requirements in view of protection of a passenger. For example, the gas generator is required to reliably operate even after ten years which correspond to normal service life of a vehicle mounted with the gas generator. Further, when the air bag is inflated and developed, it is required that the air bag is not heated excessively, combustion residue (soot) is not mixed into the air bag, and the passenger does not feel nervous or does not receive physical influence.
A coolant/filter is disposed in the gas generator to cool a high temperature combustion gas generated by combustion of a gas generating agent or collect the combustion residue. In order to reduce the gas generator in both size and weight, it is required to lighten the coolant/filter without deteriorating the cooling effect.
Further, a gas generating agent used for the gas generator does not always have high ignitability depending upon its composition. Even such a gas generating agent, it is required to start igniting and to complete ignition within a predetermined period of time, and to introduce a gas into the air bag so that a passenger is restrained at the time of collision.
Besides, in the operation process of the gas generator, if a portion of the gas generator where ignition energy from ignition means is transmitted to the gas generating agent and a portion of the gas generator where a gas generated by the combustion is discharged from the combustion chamber are close to each other, it is considered that a portion of the ignition energy is discharged from the combustion chamber as it is, or the ignition energy is transmitted to the entire gas generating agent in the combustion chamber and a portion of the gas generating agent is remained unburnt. In such a case, there is an adverse possibility that the air bag cannot sufficiently be inflated and developed.
U.S. Pat. No. 5,200,574 is prior art related to the present invention.